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Tue Rissep Pine-BorER HL 0 
to protect themselves from enemies. Toward fall, however, they construct 
about themselves a wall from débris, somewhat resembling that of the 
pupal cell. In the spring the larvae leave their winter cells for food, 
but during this second summer they usually keep themselves more or less 
protected by such a barrier. This they tear down and rebuild as they 
move about for food. As a result of this moving about, a rather extensive 
area, in the form of a blotch mine, is finally excavated. 
During the early part of August of the second year the larvae prepare 
to pupate. This they do by enlarging and strengthening the chambers 
in which they have recently been feeding, forming what are called pupal 
cells (Plate VIII, 7). These cells are oval in shape, are about $ by $ inch 
in size, and lie just underneath the bark. They are constructed of frass 
which these or other insects have discarded, and are lined with strips 
of wood which the larvae tear from the bottom of the cells and push 
firmly into their walls. The excavation of the wood insures the insects 
plenty of room as well as a better protection against their enemies. 
During late summer and early fall the second-year larvae transform to 
pupae, which in a period of from four to six weeks change to adults. They 
remain in the pupal cells over winter, emerging as adults the following 
spring. 
SEASONAL HISTORY 
Shortly after copulation, the female can be found on the bark of pine 
trees that have recently died. She walks over the bark, constantly 
searching with her ovipositor for crevices between the layers of the corky 
outer bark, in which she deposits her eggs in masses of from one to twenty- 
five or more, depending on the suitableness of the cavity (Plate VIII, 10). 
The writer found masses of eggs that hatched at different intervals, 
indicating that the insects may oviposit in the same cavity more than 
once. 
Ege laying continues from about the middle of May until the last of 
June or the first of July. Since the eggs all mature at about the same 
time, the number laid by. a single female can be easily ascertained. This 
number was found to vary from 120 to 165, indicating that the number 
is comparatively constant. 
The eggs hatch into young larvae in from eight to ten days. As soon 
as they are hatched, they work their way through the bark, where they 
feed during their larval life on the tissues of the cambium layer. 
